Continuous video in a light deficient environment

ABSTRACT

The present disclosure extends to methods, systems, and computer program products for producing an image in light deficient environments and associated structures, methods and features is disclosed and described. The features of the system may include controlling a light source through duration, intensity or both; pulsing a component controlled light source during the blanking time; maximizing the blanking time to allow optimum light; and maintaining color balance.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/952,518, filed on Jul. 26, 2013, and claims the benefit of U.S.Provisional Patent Application No. 61/676,289, filed on Jul. 26, 2012,and U.S. Provisional Patent Application No. 61/790,487, filed on Mar.15, 2013, which are hereby incorporated by reference herein in theirentireties, including but not limited to those portions thatspecifically appear hereinafter, the incorporation by reference beingmade with the following exception: In the event that any portion of theabove-referenced applications is inconsistent with this application,this application supersedes said above-referenced applications.

BACKGROUND

Advances in technology have provided advances in imaging capabilitiesfor medical use. One area that has enjoyed some of the most beneficialadvances is that of endoscopic surgical procedures because of theadvances in the components that make up an endoscope.

The disclosure relates generally to electromagnetic sensing and sensors.The disclosure also relates to low energy electromagnetic inputconditions as well as low energy electromagnetic throughput conditions.The disclosure relates more particularly, but not necessarily entirely,to a system for producing an image in light deficient environments andassociated structures, methods and features, which may includecontrolling a light source through duration, intensity or both, pulsinga component controlled light source during the blanking time, maximizingthe blanking time to allow optimum light, and maintaining color balance.

The features and advantages of the disclosure will be set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by the practice of the disclosure withoutundue experimentation. The features and advantages of the disclosure maybe realized and obtained by means of the instruments and combinationsparticularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive implementations of the disclosure aredescribed with reference to the following figures, wherein likereference numerals refer to like parts throughout the various viewsunless otherwise specified. Advantages of the disclosure will becomebetter understood with regard to the following description andaccompanying drawings where:

FIG. 1 is a schematic view of an embodiment of a system of a pairedsensor and an electromagnetic emitter in operation for use in producingan image in a light deficient environment made in accordance with theprinciples and teachings of the disclosure;

FIG. 2 is a schematic view of complementary system hardware;

FIGS. 2A to 2D are illustrations of the operational cycles of a sensor(e.g., a plurality of frames) used to construct one image frame inaccordance with the principles and teachings of the disclosure;

FIG. 3 is a graphical representation of the operation of an embodimentof an electromagnetic emitter in accordance with the principles andteachings of the disclosure;

FIG. 4 is a graphical representation of varying the duration andmagnitude of the emitted electromagnetic pulse in order to provideexposure control in accordance with the principles and teachings of thedisclosure;

FIG. 5 is a graphical representation of an embodiment of the disclosurecombining the operational cycles of a sensor, the electromagneticemitter and the emitted electromagnetic pulses of FIGS. 2A-4, whichdemonstrate the imaging system during operation in accordance with theprinciples and teachings of the disclosure;

FIG. 6 illustrates a schematic of two distinct processes over a periodof time from t(0) to t(1) for recording an image frame of a video streamfor full spectrum light and partitioned spectrum light in accordancewith the principles and teachings of the disclosure;

FIGS. 7A-7E illustrate schematic views of the processes over an intervalof time for recording an image frame of a video stream for both fullspectrum light and partitioned spectrum light in accordance with theprinciples and teachings of the disclosure;

FIGS. 8-12 illustrate the adjustment of both the electromagnetic emitterand the sensor, wherein such adjustment may be made concurrently in someembodiments in accordance with the principles and teachings of thedisclosure;

FIGS. 13-21 illustrate sensor correction methods and hardware schematicsfor use with a partitioned light system in accordance with theprinciples and teachings of the disclosure;

FIGS. 22-23 illustrate method and hardware schematics for increasing thedynamic range within a closed or limited light environment in accordancewith the principles and teachings of the disclosure;

FIG. 24 illustrates the impact on signal to noise ratio of the colorcorrection for a typical Bayer-based sensor compared with no colorcorrection;

FIG. 25 illustrates the chromaticity of 3 monochromatic lasers comparedto the sRGB gamut;

FIGS. 26-27B illustrate method and hardware schematics for increasingthe dynamic range within a closed or limited light environment inaccordance with the principles and teachings of the disclosure;

FIGS. 28A-28C illustrate the use of a white light emission that ispulsed and/or synced with a corresponding color sensor;

FIGS. 29A and 29B illustrate an implementation having a plurality ofpixel arrays for producing a three dimensional image in accordance withthe teachings and principles of the disclosure;

FIGS. 30A and 30B illustrate a perspective view and a side view,respectively, of an implementation of an imaging sensor built on aplurality of substrates, wherein a plurality of pixel columns formingthe pixel array are located on the first substrate and a plurality ofcircuit columns are located on a second substrate and showing anelectrical connection and communication between one column of pixels toits associated or corresponding column of circuitry;

FIGS. 31A and 31B illustrate a perspective view and a side view,respectively, of an implementation of an imaging sensor having aplurality of pixel arrays for producing a three dimensional image,wherein the plurality of pixel arrays and the image sensor are built ona plurality of substrates; and

FIGS. 32-36 illustrate embodiments of emitters comprising variousmechanical filter and shutter configurations.

DETAILED DESCRIPTION

The disclosure extends to methods, systems, and computer based productsfor digital imaging that may be primarily suited to medicalapplications. In the following description of the disclosure, referenceis made to the accompanying drawings, which form a part hereof, and inwhich is shown by way of illustration specific implementations in whichthe disclosure may be practiced. It is understood that otherimplementations may be utilized and structural changes may be madewithout departing from the scope of the disclosure.

Conventional endoscopes, used in, for example, arthroscopy andlaparoscopy, are designed such that the image sensors are typicallyplaced within a hand-piece unit. In such a configuration, an endoscopeunit must transmit the incident light along its length toward the sensorvia a complex set of precisely coupled optical components, with minimalloss and distortion. The cost of the endoscope unit is dominated by theoptics, since the components are expensive and the manufacturing processis labor intensive. Moreover, this type of scope is mechanicallydelicate and relatively minor impacts can easily damage the componentsor upset the relative alignments thereof, thereby causing extensivelight fall off and rendering the scope unusable. This necessitatesfrequent, expensive repair cycles in order to maintain image quality.One solution to this issue is to place the image sensor within theendoscope itself at the distal end, thereby potentially approaching theoptical simplicity, robustness and economy that is universally realizedwithin, for example, mobile phone cameras. An acceptable solution tothis approach is by no means trivial, however, as it introduces its ownset of engineering challenges, not the least of which is the fact thatthe sensor must fit within an area that is highly confined, particularlyin the X and Y dimensions, while there is more freedom in the Zdimension.

Placing aggressive constraints on sensor area naturally results in fewerand/or smaller pixels within a pixel array. Lowering the pixel count maydirectly affect the spatial resolution, while reducing the pixel areamay reduce the available signal capacity and thereby the sensitivity ofthe pixel, as well as optimizing the number of pixels such that imagequality is maximized, the minimum pixel resolution and native number ofpixels using the maximum pixel quality and pitch, such that resolutionis not an issue as well as lowering the signal to noise ratio (SNR) ofeach pixel. Lowering the signal capacity reduces the dynamic range,i.e., the ability of the imaging device or camera to simultaneouslycapture all of the useful information from scenes with large ranges ofluminosity. There are various methods to extend the dynamic range ofimaging systems beyond that of the pixel itself. All of them may havesome kind of penalty, however, (e.g., in resolution or frame rate) andthey can introduce undesirable artifacts, which become problematic inextreme cases. Reducing the sensitivity has the consequence that greaterlight power is required to bring the darker regions of the scene toacceptable signal levels. Lowering the F-number (enlarging the aperture)can compensate for a loss in sensitivity, but at the cost of spatialdistortion and reduced depth of focus.

In the sensor industry, CMOS image sensors have largely displacedconventional CCD image sensors in modern camera applications, such asendoscopy, owing to their greater ease of integration and operation,superior or comparable image quality, greater versatility and lowercost. Typically, they may include the circuitry necessary to convert theimage information into digital data and have various levels of digitalprocessing incorporated thereafter. This can range from basic algorithmsfor the purpose of correcting non-idealities, which may, for example,arise from variations in amplifier behavior, to full image signalprocessing (ISP) chains, providing video data in the standard sRGB colorspace for example (cameras-on-chip).

If the control unit or second stage is remotely located with respect toand is an appreciable distance from the sensor, it may be desirable totransmit the data in the digital domain, since it is largely immune tointerference noise and signal degradation, when compared to transmittingan analog data stream. It will be appreciated that various electricaldigital signaling standards may be used, such as LVDS (low voltagedifferential signaling), sub-LVDS, SLVS (scalable low voltage signaling)or other electrical digital signaling standards.

There may be a strong desire to minimize the number of electricalconductors in order to reduce the number of pads consuming space on thesensor, and to reduce the complexity and cost of sensor manufacture.Although the addition of analog to digital conversion to the sensor maybe advantageous, the additional area occupied by the conversion circuitsis offset because of the significant reduction in the analog bufferingpower needed due to the early conversion to a digital signal.

In terms of area consumption, given the typical feature size availablein CMOS image sensor (CIS) technologies, it may be preferable in someimplementations to have all of the internal logic signals generated onthe same chip as the pixel array via a set of control registers and asimple command interface.

Some implementations of the disclosure may include aspects of a combinedsensor and system design that allows for high definition imaging withreduced pixel counts in a highly controlled illumination environment.This may be accomplished by virtue of frame by frame pulsing of a singlecolor wavelength and switching or alternating each frame between asingle, different color wavelength using a controlled light source inconjunction with high frame capture rates and a specially designedcorresponding monochromatic sensor. As used herein monochramitc sensorrefers to an unfiltered imaging sensor. Since the pixels are coloragnostic, the effective spatial resolution is appreciably higher thanfor their color (typically Bayer-pattern filtered) counterparts inconventional single-sensor cameras. They may also have higher quantumefficiency since far fewer incident photons are wasted between theindividual pixels. Moreover, Bayer based spatial color modulationrequires that the modulation transfer function (MTF) of the accompanyingoptics be lowered compared with the monochrome modulation, in order toblur out the color artifacts associated with the Bayer pattern. This hasa detrimental impact on the actual spatial resolution that can berealized with color sensors.

The disclosure is also concerned with a system solution for endoscopyapplications in which the image sensor is resident at the distal end ofthe endoscope. In striving for a minimal area sensor based system, thereare other design aspects that can be developed, beyond reduction inpixel count. The area of the digital portion of the chip may beminimized. In addition, the number of connections to the chip (pads) mayalso be minimized. The disclosure describes novel methods thataccomplish these goals for the realization of such a system. Thisinvolves the design of a full-custom CMOS image sensor with severalnovel features.

For the purposes of promoting an understanding of the principles inaccordance with the disclosure, reference will now be made to theembodiments illustrated in the drawings and specific language will beused to describe the same. It will nevertheless be understood that nolimitation of the scope of the disclosure is thereby intended. Anyalterations and further modifications of the inventive featuresillustrated herein, and any additional applications of the principles ofthe disclosure as illustrated herein, which would normally occur to oneskilled in the relevant art and having possession of this disclosure,are to be considered within the scope of the disclosure claimed.

Before the structure, systems and methods for producing an image in alight deficient environment are disclosed and described, it is to beunderstood that this disclosure is not limited to the particularstructures, configurations, process steps, and materials disclosedherein as such structures, configurations, process steps, and materialsmay vary somewhat. It is also to be understood that the terminologyemployed herein is used for the purpose of describing particularembodiments only and is not intended to be limiting since the scope ofthe disclosure will be limited only by the appended claims andequivalents thereof.

In describing and claiming the subject matter of the disclosure, thefollowing terminology will be used in accordance with the definitionsset out below.

It must be noted that, as used in this specification and the appendedclaims, the singular forms “a,” “an,” and “the” include plural referentsunless the context clearly dictates otherwise.

As used herein, the terms “comprising,” “including,” “containing,”“characterized by,” and grammatical equivalents thereof are inclusive oropen-ended terms that do not exclude additional, unrecited elements ormethod steps.

As used herein, the phrase “consisting of” and grammatical equivalentsthereof exclude any element or step not specified in the claim.

As used herein, the phrase “consisting essentially of” and grammaticalequivalents thereof limit the scope of a claim to the specifiedmaterials or steps and those that do not materially affect the basic andnovel characteristic or characteristics of the claimed disclosure.

As used herein, the term “proximal” shall refer broadly to the conceptof a portion nearest an origin.

As used herein, the term “distal” shall generally refer to the oppositeof proximal, and thus to the concept of a portion farther from anorigin, or a furthest portion, depending upon the context.

As used herein, color sensors or multi spectrum sensors are thosesensors known to have a color filter array (CFA) thereon so as to filterthe incoming electromagnetic radiation into its separate components. Inthe visual range of the electromagnetic spectrum, such a CFA may bebuilt on a Bayer pattern or modification thereon in order to separategreen, red and blue spectrum components of the light. Referring now toFIGS. 1-5, the systems and methods for producing an image in a lightdeficient environment will now be described. FIG. 1 illustrates aschematic view of a paired sensor and an electromagnetic emitter inoperation for use in producing an image in a light deficientenvironment. Such a configuration allows for increased functionality inlight controlled or ambient light deficient environments.

It should be noted that as used herein the term “light” is both aparticle and a wavelength, and is intended to denote electromagneticradiation that is detectable by a pixel array, and may includewavelengths from the visible and non-visible spectrums ofelectromagnetic radiation. The term “partition” is used herein to mean apredetermined range of wavelengths of the electromagnetic spectrum thatis less than the entire spectrum, or in other words, wavelengths thatmake up some portion of the electromagnetic spectrum. As used herein, anemitter is a light source that may be controllable as to the portion ofthe electromagnetic spectrum that is emitted or that may operate as tothe physics of its components, the intensity of the emissions, or theduration of the emission, or all of the above. An emitter may emit lightin any dithered, diffused, or collimated emission and may be controlleddigitally or through analog methods or systems. As used herein, anelectromagnetic emitter is a source of a burst of electromagnetic energyand includes light sources, such as lasers, LEDs, incandescent light, orany light source that can be digitally controlled.

A pixel array of an image sensor may be paired with an emitterelectronically, such that they are synced during operation for bothreceiving the emissions and for the adjustments made within the system.As can be seen in FIG. 1, an emitter 100 may be tuned to emitelectromagnetic radiation in the form of a laser, which may be pulsed inorder to illuminate an object 110. The emitter 100 may pulse at aninterval that corresponds to the operation and functionality of a pixelarray 122. The emitter 100 may pulse light in a plurality ofelectromagnetic partitions 105, such that the pixel array receiveselectromagnetic energy and produces a data set that corresponds (intime) with each specific electromagnetic partition 105. For example,FIG. 1 illustrates a system having a monochromatic sensor 120 having apixel array (black and white) 122 and supporting circuitry, which pixelarray 122 is sensitive to electromagnetic radiation of any wavelength.The light emitter 100 illustrated in the figure may be a laser emitterthat is capable of emitting a red electromagnetic partition 105 a, ablue electromagnetic partition 105 b, and a green electromagneticpartition 105 c in any desired sequence. It will be appreciated thatother light emitters 100 may be used in FIG. 1 without departing fromthe scope of the disclosure, such as digital or analog based emitters.

During operation, the data created by the monochromatic sensor 120 forany individual pulse may be assigned a specific color partition, whereinthe assignment is based on the timing of the pulsed color partition fromthe emitter 100. Even though the pixels 122 are not color dedicated theycan be assigned a color for any given data set based on a prioriinformation about the emitter.

In one embodiment, three data sets representing RED, GREEN and BLUEelectromagnetic pulses may be individual frames combined to form asingle image frame. It will be appreciated that the disclosure is notlimited to any particular color combination or any particularelectromagnetic partition, and that any color combination or anyelectromagnetic partition may be used in place of RED, GREEN and BLUE,such as Cyan, Magenta and Yellow; Ultraviolet; infra-red; anycombination of the foregoing, or any other color combination, includingall visible and non-visible wavelengths, without departing from thescope of the disclosure. In the figure, the object 110 to be imagedcontains a red portion 110 a, green portion 110 b and a blue portion 110c. As illustrated in the figure, the reflected light from theelectromagnetic pulses only contains the data for the portion of theobject having the specific color that corresponds to the pulsed colorpartition. Those separate color (or color interval) data sets can thenbe used to reconstruct the image by combining the data sets at 130.

As illustrated in FIG. 2, implementations of the present disclosure maycomprise or utilize a special purpose or general-purpose computer,including computer hardware, such as, for example, one or moreprocessors and system memory, as discussed in greater detail below.Implementations within the scope of the present disclosure may alsoinclude physical and other computer-readable media for carrying orstoring computer-executable instructions and/or data structures. Suchcomputer-readable media can be any available media that can be accessedby a general purpose or special purpose computer system.Computer-readable media that store computer-executable instructions arecomputer storage media (devices). Computer-readable media that carrycomputer-executable instructions are transmission media. Thus, by way ofexample, and not limitation, implementations of the disclosure cancomprise at least two distinctly different kinds of computer-readablemedia: computer storage media (devices) and transmission media.

Computer storage media (devices) includes RAM, ROM, EEPROM, CD-ROM,solid state drives (“SSDs”) (e.g., based on RAM), Flash memory,phase-change memory (“PCM”), other types of memory, other optical diskstorage, magnetic disk storage or other magnetic storage devices, or anyother medium which can be used to store desired program code means inthe form of computer-executable instructions or data structures andwhich can be accessed by a general purpose or special purpose computer.

A “network” is defined as one or more data links that enable thetransport of electronic data between computer systems and/or modulesand/or other electronic devices. In an implementation, a sensor andcamera control unit may be networked in order to communicate with eachother, and other components, connected over the network to which theyare connected. When information is transferred or provided over anetwork or another communications connection (either hardwired,wireless, or a combination of hardwired or wireless) to a computer, thecomputer properly views the connection as a transmission medium.Transmissions media can include a network and/or data links, which canbe used to carry desired program code means in the form ofcomputer-executable instructions or data structures and which can beaccessed by a general purpose or special purpose computer. Combinationsof the above should also be included within the scope ofcomputer-readable media.

Further, upon reaching various computer system components, program codemeans in the form of computer-executable instructions or data structuresthat can be transferred automatically from transmission media tocomputer storage media (devices) (or vice versa). For example,computer-executable instructions or data structures received over anetwork or data link can be buffered in RAM within a network interfacemodule (e.g., a “NIC”), and then eventually transferred to computersystem RAM and/or to less volatile computer storage media (devices) at acomputer system. RAM can also include solid state drives (SSDs or PCIxbased real time memory tiered storage, such as FusionIO). Thus, itshould be understood that computer storage media (devices) can beincluded in computer system components that also (or even primarily)utilize transmission media.

Computer-executable instructions comprise, for example, instructions anddata which, when executed at a processor, cause a general purposecomputer, special purpose computer, or special purpose processing deviceto perform a certain function or group of functions. The computerexecutable instructions may be, for example, binaries, intermediateformat instructions such as assembly language, or even source code.Although the subject matter has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the described features or acts described above.Rather, the described features and acts are disclosed as example formsof implementing the claims.

Those skilled in the art will appreciate that the disclosure may bepracticed in network computing environments with many types of computersystem configurations, including, personal computers, desktop computers,laptop computers, message processors, control units, camera controlunits, hand-held devices, hand pieces, multi-processor systems,microprocessor-based or programmable consumer electronics, network PCs,minicomputers, mainframe computers, mobile telephones, PDAs, tablets,pagers, routers, switches, various storage devices, and the like. Itshould be noted that any of the above mentioned computing devices may beprovided by or located within a brick and mortar location. Thedisclosure may also be practiced in distributed system environmentswhere local and remote computer systems, which are linked (either byhardwired data links, wireless data links, or by a combination ofhardwired and wireless data links) through a network, both performtasks. In a distributed system environment, program modules may belocated in both local and remote memory storage devices.

Further, where appropriate, functions described herein can be performedin one or more of: hardware, software, firmware, digital components, oranalog components. For example, one or more application specificintegrated circuits (ASICs) or field programmable gate arrays (FPGAs)can be programmed to carry out one or more of the systems and proceduresdescribed herein. Certain terms are used throughout the followingdescription and Claims to refer to particular system components. As oneskilled in the art will appreciate, components may be referred to bydifferent names. This document does not intend to distinguish betweencomponents that differ in name, but not function.

FIG. 2 is a block diagram illustrating an example computing device 150.Computing device 150 may be used to perform various procedures, such asthose discussed herein. Computing device 150 can function as a server, aclient, or any other computing entity. Computing device 150 can performvarious monitoring functions as discussed herein, and can execute one ormore application programs, such as the application programs describedherein. Computing device 150 can be any of a wide variety of computingdevices, such as a desktop computer, a notebook computer, a servercomputer, a handheld computer, camera control unit, tablet computer andthe like.

Computing device 150 includes one or more processor(s) 152, one or morememory device(s) 154, one or more interface(s) 156, one or more massstorage device(s) 158, one or more Input/Output (I/O) device(s) 160, anda display device 180 all of which are coupled to a bus 162. Processor(s)152 include one or more processors or controllers that executeinstructions stored in memory device(s) 154 and/or mass storagedevice(s) 158. Processor(s) 152 may also include various types ofcomputer-readable media, such as cache memory.

Memory device(s) 154 include various computer-readable media, such asvolatile memory (e.g., random access memory (RAM) 164) and/ornonvolatile memory (e.g., read-only memory (ROM) 166). Memory device(s)154 may also include rewritable ROM, such as Flash memory.

Mass storage device(s) 158 include various computer readable media, suchas magnetic tapes, magnetic disks, optical disks, solid-state memory(e.g., Flash memory), and so forth. As shown in FIG. 2, a particularmass storage device is a hard disk drive 174. Various drives may also beincluded in mass storage device(s) 158 to enable reading from and/orwriting to the various computer readable media. Mass storage device(s)158 include removable media 176 and/or non-removable media.

I/O device(s) 160 include various devices that allow data and/or otherinformation to be input to or retrieved from computing device 150.Example I/O device(s) 160 include digital imaging devices,electromagnetic sensors and emitters, cursor control devices, keyboards,keypads, microphones, monitors or other display devices, speakers,printers, network interface cards, modems, lenses, CCDs or other imagecapture devices, and the like.

Display device 180 includes any type of device capable of displayinginformation to one or more users of computing device 150. Examples ofdisplay device 180 include a monitor, display terminal, video projectiondevice, and the like.

Interface(s) 106 include various interfaces that allow computing device150 to interact with other systems, devices, or computing environments.Example interface(s) 156 may include any number of different networkinterfaces 170, such as interfaces to local area networks (LANs), widearea networks (WANs), wireless networks, and the Internet. Otherinterface(s) include user interface 168 and peripheral device interface172. The interface(s) 156 may also include one or more user interfaceelements 168. The interface(s) 156 may also include one or moreperipheral interfaces such as interfaces for printers, pointing devices(mice, track pad, etc.), keyboards, and the like.

Bus 162 allows processor(s) 152, memory device(s) 154, interface(s) 156,mass storage device(s) 158, and I/O device(s) 160 to communicate withone another, as well as other devices or components coupled to bus 162.Bus 162 represents one or more of several types of bus structures, suchas a system bus, PCI bus, IEEE 1394 bus, USB bus, and so forth.

For purposes of illustration, programs and other executable programcomponents are shown herein as discrete blocks, although it isunderstood that such programs and components may reside at various timesin different storage components of computing device 150, and areexecuted by processor(s) 152. Alternatively, the systems and proceduresdescribed herein can be implemented in hardware, or a combination ofhardware, software, and/or firmware. For example, one or moreapplication specific integrated circuits (ASICs) or field programmablegate arrays (FPGAs) can be programmed to carry out one or more of thesystems and procedures described herein.

FIG. 2A illustrates the operational cycles of an image sensor used inrolling readout mode or during the sensor readout 200. The frame readoutphase may start at and may be represented by vertical line 210. Theperiod frame readout phase is represented by the diagonal or slantedline 202. The sensor may be read out on a row by row basis, the top ofthe downwards slanted edge being the sensor top row 212 and the bottomof the downwards slanted edge being the sensor bottom row 214. The timebetween the last row readout and the next readout cycle may be calledthe blanking time 216. It should be noted that some of the sensor pixelrows might be covered with a light shield (e.g., a metal coating or anyother substantially black layer of another material type). These coveredpixel rows may be referred to as optical black rows 218 and 220. Opticalblack rows 218 and 220 may be used as input for correction algorithms.As shown in FIG. 2A, these optical black rows 218 and 220 may be locatedon the top of the pixel array or at the bottom of the pixel array or atthe top and the bottom of the pixel array. FIG. 2B illustrates a processof controlling the amount of electromagnetic radiation, e.g., light,that is exposed to a pixel, thereby integrated or accumulated by thepixel. It will be appreciated that photons are elementary particles ofelectromagnetic radiation. Photons are integrated, absorbed, oraccumulated by each pixel and converted into an electrical charge orcurrent. An electronic shutter or rolling shutter (shown by dashed line222) may be used to start the integration time by resetting the pixel.The light will then integrate until the next frame readout phase. Theposition of the electronic shutter 222 can be moved between twooperational cycles in order to control the pixel saturation for a givenamount of light. It should be noted that this technique allows for aconstant integration time between two different lines, but introduces adelay when moving from top to bottom rows. FIG. 2C illustrates the casewhere the electronic shutter 222 has been removed. In thisconfiguration, the integration of the incoming light may start duringframe readout phase 202 and may end at the next operational cycle, whichalso defines the start of the next integration. FIG. 2D shows aconfiguration without an electronic shutter 222, but with a controlledand pulsed light 230 during the blanking time 216. This ensures that allrows see the same light issued from the same light pulse 230. In otherwords, each row will start its integration in a dark environment, whichmay be at the optical black back row 220 of frame (m) for a maximumlight pulse width, and will then receive a light strobe and will end itsintegration in a dark environment, which may be at the optical blackfront row 218 of the next succeeding read (m+1) for a maximum lightpulse width. In the FIG. 2D example, the image generated from the lightpulse will be solely available during the frame readout phase of frame(m+1) without any interference with frames (m) and (m+2). It should benoted that the condition to have a light pulse to be read out only inone frame and not interfere with neighboring frames is to have the givenlight pulse firing during the blanking time 216. Because the opticalblack rows 218, 220 are insensitive to light, the time spent reading outoptical black back rows 220 of frame (m) and the time spent reading outoptical black front rows 218 of frame (m+1) can be added to the blankingtime 216 to determine the maximum range of the firing time of the lightpulse 230. As illustrated in the FIG. 2A, a sensor may be cycled manytimes in order to receive data for each pulsed color (e.g., Red, Green,Blue). Each cycle may be timed. In an embodiment, the cycles may betimed to operate within an interval of 16.67 ms. In another embodiment,the cycles may be timed to operate within an interval of 8.3 ms. It willbe appreciated that other timing intervals are contemplated by thedisclosure and are intended to fall within the scope of this disclosure.

FIG. 3 graphically illustrates the operation of an embodiment of anelectromagnetic emitter. An emitter may be timed to correspond with thecycles of a sensor, such that electromagnetic radiation is emittedwithin the sensor operation cycle and/or during a portion of the sensoroperation cycle. FIG. 3 illustrates Pulse 1 at 302, Pulse 2 at 304, andPulse 3 at 306. In an embodiment, the emitter may pulse during the framereadout phase 202 of the sensor operation cycle. In an embodiment, theemitter may pulse during the blanking time 216 of the sensor operationcycle. In an embodiment, the emitter may pulse for a duration that isduring portions of two or more sensor operational cycles. In anembodiment, the emitter may begin a pulse during the blanking time 216,or during the optical black portion 220 of the frame readout phase 202,and end the pulse during the frame readout phase 202, or during theoptical black portion 218 of the frame readout phase 202 of the nextsucceeding cycle. It will be understood that any combination of theabove is intended to fall within the scope of this disclosure as long asthe pulse of the emitter and the cycle of the sensor correspond.

FIG. 4 graphically represents varying the duration and magnitude of theemitted electromagnetic pulse (e.g., Pulse 1 at 402, Pulse 2 at 404, andPulse 3 at 406) to control exposure. An emitter having a fixed outputmagnitude may be pulsed during any of the cycles noted above in relationto FIGS. 2D and 3 for an interval to provide the needed electromagneticenergy to the pixel array. An emitter having a fixed output magnitudemay be pulsed at a longer interval of time, thereby providing moreelectromagnetic energy to the pixels or the emitter may be pulsed at ashorter interval of time, thereby providing less electromagnetic energy.Whether a longer or shorter interval time is needed depends upon theoperational conditions.

In contrast to adjusting the interval of time that the emitter pulses afixed output magnitude, the magnitude of the emission itself may beincreased in order to provide more electromagnetic energy to the pixels.Similarly, decreasing the magnitude of the pulse provides lesselectromagnetic energy to the pixels. It should be noted that anembodiment of the system may have the ability to adjust both magnitudeand duration concurrently, if desired. Additionally, the sensor may beadjusted to increase its sensitivity and duration as desired for optimalimage quality. FIG. 4 illustrates varying the magnitude and duration ofthe pulses. In the illustration, Pulse 1 at 402 has a higher magnitudeor intensity than either Pulse 2 at 404 or Pulse 3 at 406. Additionally,Pulse 1 at 402 has a shorter duration than Pulse 2 at 404 or Pulse 3 at406, such that the electromagnetic energy provided by the pulse isillustrated by the area under the pulse shown in the illustration. Inthe illustration, Pulse 2 at 404 has a relatively low magnitude orintensity and a longer duration when compared to either Pulse 1 at 402or Pulse 3 at 406. Finally, in the illustration, Pulse 3 at 406 has anintermediate magnitude or intensity and duration, when compared to Pulse1 at 402 and Pulse 2 at 404.

FIG. 5 is a graphical representation of an embodiment of the disclosurecombining the operational cycles, the electromagnetic emitter and theemitted electromagnetic pulses of FIGS. 2-4 to demonstrate the imagingsystem during operation in accordance with the principles and teachingsof the disclosure. As can be seen in the figure, the electromagneticemitter pulses the emissions primarily during the blanking time 216 ofthe sensor, such that the pixels will be charged and ready to readduring the frame readout phase 202 of the operational cycle of thesensor. The dashed line portions in the pulse (from FIG. 3) illustratethe potential or ability to emit electromagnetic energy during theoptical black portions 220 and 218 of the operational cycle of thesensor 200 if additional time is needed or desired to pulseelectromagnetic energy.

Referring now to FIGS. 6-9A, FIG. 6 illustrates a schematic of twodistinct processes over a period of time from t(0) to t(1) for recordingan image frame of video stream for full spectrum light and partitionedspectrum light. It should be noted that color sensors have a colorfilter array (CFA) for filtering out certain wavelengths of light perpixel commonly used for full spectrum light reception. An example of aCFA is a Bayer pattern. Because the color sensor may comprise pixelswithin the array that are made sensitive to a single color from withinthe full spectrum, a reduced resolution image results because the pixelarray has pixel spaces dedicated to only a single color of light withinthe full spectrum. Usually such an arrangement is formed in acheckerboard type pattern across the entire array.

In contrast, when partitioned spectrums of light are used a sensor canbe made to be sensitive or responsive to the magnitude of all lightenergy because the pixel array will be instructed that it is sensingelectromagnetic energy from a predetermined partition of the fullspectrum of electromagnetic energy in each cycle. Therefore, to form animage frame the sensor need only be cycled with a plurality frameshaving a plurality of differing partitions from within the full spectrumof light and then reassembling the frames into an image frame to displaya predetermined mixture of color values for every pixel across thearray. Accordingly, a higher resolution image frame is also providedbecause there are reduced distances as compared to a Bayer sensorbetween pixel centers of the same color sensitivity for each of thecolor pulses. As a result, the formed colored image frame has a highermodulation transfer function (MTF). Because the image from each frame,has a higher resolution, the resultant image created when a plurality offrames are combined into a full color image frame, also has a higherresolution. In other words, because each and every pixel within thearray (instead of, at most, every second pixel in a sensor with colorfilter) is sensing the magnitudes of energy for a given pulse and agiven scene, just fractions of time apart, a higher resolution imageframe is created for each scene with less derived (less accurate) dataneeding to be introduced.

For example, white or full spectrum visible light is a combination ofred, green and blue light. In the embodiment shown in FIG. 6, it can beseen that in both the partitioned spectrum process 620 and full spectrumprocess 610 the time to capture an image is t(0) to t(1). In the fullspectrum process 610, white light or full spectrum electromagneticenergy is emitted at 612. At 614, the white or full spectrumelectromagnetic energy is sensed. At 616, the image is processed anddisplayed. Thus, between time t(0) and t(1), the image has beenprocessed and displayed. Conversely, in the partitioned spectrum process620, a first partition is emitted at 622 and sensed at 624. At 626, asecond partition is emitted and then sensed at 628. At 630, a thirdpartition is emitted and sensed at 632. At 634, the image is processedand displayed. It will be appreciated that any system using an imagesensor cycle that is at least two times faster than the white lightcycle is intended to fall within the scope of the disclosure.

As can be seen graphically in the embodiment illustrated in FIG. 6between times t(0) and t(1), the sensor for the partitioned spectrumsystem 620 has cycled three times for every one of the full spectrumsystem. In the partitioned spectrum system 620, the first of the threesensor cycles is for a green spectrum 622 and 624, the second of thethree is for a red spectrum 626 and 628, and the third is for a bluespectrum 630 and 632. Thus, in an embodiment, wherein the display device(LCD panel) operates at 50-60 image frames per second, a partitionedlight system should operate at 150-180 frames per second to produce the50-60 image frames per second and maintain the continuity and smoothnessof the displayed video stream.

In other embodiments there may be different frame capture rates andimage frame display rates. Furthermore, the average frame capture ratecould be any multiple of the image frame display rate.

In an embodiment it may be desired that not all partitions berepresented equally within the system frame rate. In other words, notall light sources have to be pulsed with the same regularity so as toemphasize and de-emphasize aspects of the recorded scene as desired bythe users. It should also be understood that non-visible and visiblepartitions of the electromagnetic spectrum may be pulsed together withina system with their respective data value being stitched into the videooutput as desired for display to a user.

An embodiment may comprise a pulse cycle pattern as follows:

-   -   Green pulse;    -   Red pulse;    -   Blue pulse;    -   Green pulse;    -   Red pulse;    -   Blue pulse;    -   Infra-red (IR) pulse;    -   (Repeat)

As can be seen in the example, an IR partition may be pulsed at a ratediffering from the rates of the other partition pulses. This may be doneto emphasize a certain aspect of the scene, with the IR data simplybeing overlaid with the other data in the video output to make thedesired emphasis. It should be noted that the addition of a fourthelectromagnetic partition does not necessarily require the serializedsystem to operate at four times the rate of a full spectrum non-serialsystem because every partition does not have to be represented equallyin the pulse pattern. As seen in the embodiment, the addition of apartition pulse that is represented less in a pulse pattern (IR in theabove example), would result in an increase of less than 20% of thecycling speed of the sensor in order accommodate the irregular partitionsampling.

In an embodiment, an electromagnetic partition may be emitted that issensitive to dyes or materials that are used to highlight aspects of ascene. In the embodiment it may be sufficient to highlight the locationof the dyes or materials without need for high resolution. In such anembodiment, the dye sensitive electromagnetic partition may be cycledmuch less frequently than the other partitions in the system in order toinclude the emphasized data.

The partition cycles may be divided so as to accommodate or approximatevarious imaging and video standards. In an embodiment, the partitioncycles may comprise pulses of electromagnetic energy in the Red, Green,Blue spectrum as follows as illustrated best in FIGS. 7A-7D. In FIG. 7A,the different light intensities have been achieved by modulating thelight pulse width or duration within the working range shown by thevertical grey dashed lines. In FIG. 7B, the different light intensitieshave been achieved by modulating the light power or the power of theelectromagnetic emitter, which may be a laser or LED emitter, butkeeping the pulse width or duration constant. FIG. 7C shows the casewhere both the light power and the light pulse width are beingmodulated, leading to greater flexibility. The partition cycles may useCMY, IR and ultraviolet using a non-visible pulse source mixed withvisible pulse sources and any other color space required to produce animage or approximate a desired video standard that is currently known oryet to be developed. It should also be understood that a system may beable to switch between the color spaces on the fly in order to providethe desired image output quality.

In an embodiment using color spaces Green-Blue-Green-Red (as seen inFIG. 7D) it may be desirous to pulse the luminance components more oftenthan the chrominance components because users are generally moresensitive to light magnitude differences than to light colordifferences. This principle can be exploited using a mono-chromaticsensor as illustrated in FIG. 7D. In FIG. 7D, green, which contains themost luminance information, may be pulsed more often or with moreintensity in a (G-B-G-R-G-B-G-R . . . ) scheme to obtain the luminancedata. Such a configuration would create a video stream that hasperceptively more detail, without creating and transmittingunperceivable data.

In an embodiment, duplicating the pulse of a weaker partition may beused to produce an output that has been adjusted for the weaker pulse.For example, blue laser light is considered weak relative to thesensitivity of silicon based pixels and is difficult to produce incomparison to the red or green light, and therefore may be pulsed moreoften during an image frame cycle to compensate for the weakness of thelight. These additional pulses may be done serially over time or byusing multiple lasers that simultaneously pulse to produce the desiredcompensation effect. It should be noted that by pulsing during blankingtime (time during which the sensor is not reading out the pixel array),the sensor is insensitive to differences/mismatches between lasers ofthe same kind and simply accumulates the light for the desired output.In another embodiment, the maximum light pulse range may be differentfrom frame to frame. This is shown in FIG. 7E where the light pulses aredifferent from frame to frame. The sensor may be built in order to beable to program different blanking times with a repeating pattern of 2or 3 or 4 or n frames. In FIG. 7E, 4 different light pulses areillustrated and Pulse 1 may repeat for example after Pulse 4, and mayhave a pattern of 4 frames with different blanking times. This techniquecan be used to place the most powerful partition on the smallestblanking time and therefore allow the weakest partition to have widerpulse on one of the next frames without the need of increasing thereadout speed. The image frame can still have a regular pattern fromframe to frame as it is constituted of many frames.

As can be seen in FIG. 8, because each partitioned spectrum of light mayhave different energy values, the sensor and/or light emitter may beadjusted to compensate for the differences in the energy values. At 810,the data obtained from the histogram from a previous frame may beanalyzed. At 820, the sensor may be adjusted as noted below.Additionally, at 830, the emitter may be adjusted. At 840, the image maybe obtained from the adjusted sample time from the sensor or the imagemay be obtained with adjusted (either increased or decreased) emittedlight, or a combination of the above. For example, because the red lightspectrum is more readily detected by a sensor within the system than theblue light spectrum, the sensor can be adjusted to be less sensitiveduring the red partition cycle and more sensitive during the bluepartition cycle because of the low Quantum Efficiency that the bluepartition has with respect to silicon (illustrated best in FIG. 9).Similarly, the emitter may be adjusted to provide an adjusted partition(e.g., higher or lower intensity and duration). Further, adjustments maybe made at the sensor and emitter level both. The emitter may also bedesigned to emit at one specific frequency or may be changed to emitmultiple frequencies of a specific partition to broaden the spectrum oflight being emitted, if desired for a particular application.

FIG. 10 shows a schematic of an unshared 4 T pixel. The TX signal isused to transfer accumulated charges from the photo diode (PPD) to thefloating diffusion (FD). The reset signal is used to reset the FD to thereset bus. If reset and TX signals are “On” at the same time, the PPD isconstantly reset (each photo charge generated in the PPD is directlycollected at the reset bus) and the PPD is always empty. Usual pixelarray implementation includes a horizontal reset line that attaches thereset signals of all pixels within one row and a horizontal TX line thatattaches the TX signals of all pixels within one row.

In an embodiment, timing of the sensor sensibility adjustment isillustrated and sensor sensibility adjustment can be achieved using aglobal reset mechanism (i.e., a means of firing all pixel array resetsignals at once) and a global TX mechanism (i.e., a means of firing allpixel array TX signals at once). This is shown in FIG. 11. In this case,the light pulse is constant in duration and amplitude, but the lightintegrated in all pixels starts with the “on” to “off” transition of theglobal TX and ends with the light pulse. Therefore, the modulation isachieved by moving the falling edge of the global TX pulse.

Conversely, the emitter may emit red light at a lesser intensity thanblue light in order to produce a correctly exposed image (illustratedbest in FIG. 12). At 1210, the data obtained from the histogram from aprevious frame may be analyzed. At 1220, the emitter may be adjusted. At1230, the image may be obtained from the adjusted emitted light.Additionally, in an embodiment both the emitter and the sensor can beadjusted concurrently.

Reconstructing the partitioned spectrum frames into a full spectrumimage frame for later output could be as simple as blending the sensedvalues for each pixel in the array in some embodiments. Additionally,the blending and mixing of values may be simple averages, or may betuned to a predetermined lookup table (LUT) of values for desiredoutputs. In an embodiment of a system using partitioned light spectrums,the sensed values may be post-processed or further refined remotely fromthe sensor by an image or secondary processor, and just before beingoutput to a display.

FIG. 13 illustrates a basic example at 1300 of a monochrome ISP and howan ISP chain may be assembled for the purpose of generating sRGB imagesequences from raw sensor data, yielded in the presence of the G-R-G-Blight pulsing scheme.

The first stage is concerned with making corrections (see 1302, 1304 and1306 in FIG. 13) to account for any non-idealities in the sensortechnology for which it is most appropriate to work in the raw datadomain (see FIG. 21).

At the next stage, two frames (see 1308 and 1310 in FIG. 13) would bebuffered since each image frame derives data from three raw frames. Theimage frame reconstruction at 1314 would proceed by sampling data fromthe current frame and the two buffered frames (1308 and/or 1310). Theimage frame reconstruction process results in full color image frames inlinear RGB color space.

In this example, the white balance coefficients at 1318 and colorcorrection matrix at 1320 are applied before converting to YCbCr spaceat 1322 for subsequent edge enhancement at 1324. After edge enhancementat 1324, images are transformed back to linear RGB at 1326 for scalingat 1328, if applicable.

Finally, the gamma transfer function at 1330 would be applied totranslate the data into the sRGB domain at 1332.

FIG. 14 is an embodiment example of color fusion hardware. The colorfusion hardware takes in an RGBGRGBGRGBG video data stream at 1402 andconverts it to a parallel RGB video data stream at 1405. The bit widthon the input side may be, e.g., 12 bits per color. The output width forthat example would be 36 bits per pixel. Other embodiments may havedifferent initial bit widths and 3 times that number for the outputwidth. The memory writer block takes as its input the RGBG video streamat 1402 and writes each frame to its correct frame memory buffer at 1404(the memory writer triggers off the same pulse generator 1410 that runsthe laser light source). As illustrated at 1404, writing to the memoryfollows the pattern, Red, Green 1, Blue, Green 2, and then starts backwith Red again. At 1406, the memory reader reads three frames at once toconstruct an RGB pixel. Each pixel is three times the bit width of anindividual color component. The reader also triggers off the laser pulsegenerator at 1410. The reader waits until Red, Green 1 and Blue frameshave been written, then proceeds to read them out in parallel while thewriter continues writing Green 2 and starts back on Red. When Redcompletes the reader begins reading from Blue, Green 2 and Red. Thispattern continues indefinitely.

Referring now to FIGS. 15 and 16, the RG1BG2RG1BG2 patternreconstruction illustrated in FIG. 16 allows 60 fps (image frames persecond) output with 120 fps (frames per second) input in an embodiment.Each consecutive frame contains either a red or blue component from theprevious frame. In FIG. 16, each color component is available in 8.3 msand the resulting image frame has a period of 16.67 ms. In general forthis pulsing scheme, the image frame has a period twice of that of theincoming colored frame as shown in FIG. 15. In other embodiments,different pulsing schemes may be employed. For example, embodiments maybe based on the timing of each color component or frame (T1) and theimage frame having a period twice that of the incoming color frame(2xT1). Different frames within the sequence may have different frameperiods and the average capture rate could be any multiple of the finalimage frame rate.

FIGS. 17-20 illustrate color correction methods and hardware schematicsfor use with a partitioned light system. It is common in digital imagingto manipulate the values within image data in order to correct theoutput to meet user expectations or to highlight certain aspects of theimaged object. Most commonly this is done in satellite images that aretuned and adjusted to emphasize one data type over another. Most often,in satellite acquired data there is the full spectrum of electromagneticenergy available because the light source is not controlled, i.e., thesun is the light source. In contrast, there are imaging conditions wherethe light is controlled and even provided by a user. In such situations,calibration of the image data is still desirable, because withoutcalibration improper emphasis may be given to certain data over otherdata. In a system where the light is controlled by the user, it isadvantageous to provide emissions of light that are known to the user,and may be only a portion of the electromagnetic spectrum or a pluralityof portions of the full electromagnetic spectrum. Calibration remainsimportant in order to meet the expectations of the users and check forfaults within the system. One method of calibration can be a table ofexpected values for a given imaging condition that can be compared tothe data from the sensor. An embodiment may include a color neutralscene having known values that should be output by the imaging deviceand the device may be adjusted in order to meet those known values whenthe device samples the color neutral scene.

In use, and upon start up, the system may sample a color neutral sceneat 1710 (as illustrated in FIG. 17) by running a full cycle of aplurality of electromagnetic spectrum partitions at 1702. A table ofvalues 1708 may be formed to produce a histogram for the frame at 1704.The values of the frame can be compared to the known or expected valuesfrom the color neutral scene at 1706. The imaging device may then beadjusted to meet the desired output at 1712. In an embodimentillustrated in FIG. 17, the system may comprise an image signalprocessor (ISP) that may be adjusted to color correct the imagingdevice.

It should be noted that because each partitioned spectrum of light mayhave different energy values, the sensor and/or light emitter may beadjusted to compensate for the differences in the energy values. Forexample in an embodiment, because the blue light spectrum has a lowerquantum efficiency than the red light spectrum with regard to siliconbased imagers, the sensor's responsiveness can then be adjusted to beless responsive during the red cycle and more responsive during the bluecycle. Conversely, the emitter may emit blue light at a higherintensity, because of the lower quantum efficiency of the blue light,than red light in order to produce a correctly exposed image.

In an embodiment illustrated in FIG. 18, where the light sourceemissions are provided and controllable by the system, adjustment ofthose light emissions can be made in order to color correct an image at1800. Adjustments may be made to any aspect of the emitted light such asmagnitude, duration (i.e., time-on), or the range within the spectrumpartition. Additionally, both the emitter and the sensor can be adjustedconcurrently in some embodiments as shown in FIG. 19.

In order to reduce the amount of noise and artifacts within theoutputted image stream or video, fractionalized adjustments may be madeto the sensor or emitter within the system as can be seen in FIG. 20.Illustrated in FIG. 20 is a system 2000 where both the emitter 2006 andthe sensor 2008 can be adjusted, but an imaging device where either theemitter or sensor is adjusted during use or for a portion of use is alsocontemplated and is within the scope of this disclosure. It may beadvantageous to adjust only the emitter during one portion of use andadjust only the sensor during another portion of use, while further yetadjusting both concurrently during a portion of use. In any of the aboveembodiments, improved image quality may be obtained by limiting theoverall adjustments that the system can make between frame cycles. Inother words, an embodiment may be limited such that the emitter may onlybe adjusted a fraction of its operational range at any time betweenframes. Likewise, the sensor may be limited such that it may only beadjusted a fraction of its operational range at any time between frames.Furthermore, both the emitter and sensor may be limited such that theymay only be adjusted together at a fraction of their respectiveoperational ranges at any time between frames in an embodiment.

In an exemplary embodiment, a fractional adjustment of the componentswithin the system may be performed, for example, at about 0.1 dB of theoperational range of the components in order to correct the exposure ofthe previous frame. The 0.1 dB is merely an example and it should benoted that is other embodiments the allowed adjustment of the componentsmay be any portion of their respective operational ranges. Thecomponents of the system can change by intensity or duration adjustmentthat is generally governed by the number of bits (resolution) output bythe component. The component resolution may be typically between a rangeof about 10-24 bits, but should not be limited to this range as it isintended to include resolutions for components that are yet to bedeveloped in addition to those that are currently available. Forexample, after a first image frame it is determined that the scene istoo blue when observed, then the emitter may be adjusted to decrease themagnitude or duration of the pulse of the blue light during the bluecycle of the system by a fractional adjustment as discussed above, suchas about 0.1 dB.

In this exemplary embodiment, more than 10 percent may have been needed,but the system has limited itself to 0.1 dB adjustment of theoperational range per system cycle. Accordingly, during the next systemcycle the blue light can then be adjusted again, if needed.Fractionalized adjustment between cycles may have a damping effect ofthe outputted imaged and will reduce the noise and artifacts whenoperating emitters and sensors at their operation extremes. It may bedetermined that any fractional amount of the components' operationalrange of adjustment may be used as a limiting factor, or it may bedetermined that certain embodiments of the system may comprisecomponents that may be adjusted over their entire operational range.

Additionally, the optical black area of any image sensor may be used toaid in image correction and noise reduction. In an embodiment, thevalues read from the optical black area may be compared to those of theactive pixel region of a sensor in order to establish a reference pointto be used in image data processing. FIG. 21 shows the kind of sensorcorrection processes that might be employed in a color pulsed system.CMOS image sensors typically have multiple non-idealities that have adetrimental effect on image quality, particularly in low light. Chiefamong these are fixed pattern noise and line noise. Fixed pattern noiseis a dispersion in the offsets of the sense elements. Typically most ofthe FPN is a pixel to pixel dispersion which stems, among other sources,from random variations in dark current from photodiode to photodiode.This looks very unnatural to the viewer. Even more egregious is columnFPN, resulting from offsets in the readout chain associated with aparticular columns of pixels. This results in perceived vertical stripeswithin the image.

Being in total control of the illumination has the benefit that entireframes of dark data may periodically be acquired and used to correct forthe pixel and column offsets. In the illustrated example, a single framebuffer may be used to make a running average of the whole frame withoutlight using, e.g., simple exponential smoothing. This dark average framewould be subtracted from every illuminated frame during regularoperation.

Line-Noise is a stochastic temporal variation in the offsets of pixelswithin each row. Since it is temporal, the correction must be computedanew for each line and each frame. For this purpose there are usuallymany optically blind (OB) pixels within each row in the array, whichmust first be sampled to assess the line offset before sampling thelight sensitive pixels. The line offset is then simply subtracted duringthe line noise correction process.

In the example in FIG. 21, there are other corrections concerned withgetting the data into the proper order, monitoring and controlling thevoltage offset in the analog domain (black clamp) andidentifying/correcting individual defective pixels.

FIGS. 22 and 23 illustrate method and hardware schematics for increasingthe dynamic range within a closed or limited light environment. In anembodiment, exposure inputs may be input at different levels over timeand combine in order to produce greater dynamic range. As can be seen inFIG. 22, an imaging system may be cycled at a first intensity for afirst frame cycle at 2202 and then subsequently cycled at a secondintensity for a second frame cycle at 2204, and then by combining thosefirst and second cycles into a single image frame at 2206 so thatgreater dynamic range can be achieved. Greater dynamic range may beespecially desirable because of the limited space environment in whichan imaging device is used. In limited space environments that are lightdeficient or dark, except for the light provided by the light source,and where the light source is close to the light emitter, exposure hasan exponential relationship to distance. For example, objects near thelight source and optical opening of the imaging device tend to be overexposed, while objects farther away tend to be extremely under exposedbecause there is very little (in any) ambient light present.

As can be seen in FIG. 23, the cycles of a system having emissions ofelectromagnetic energy in a plurality of partitions (e.g., frames) maybe serially cycled according to the partitions of electromagneticspectrum at 2300. For example, in an embodiment where the emitter emitslasers in a distinct red partition, a distinct blue partition, and adistinct green partition, the two frame cycle data sets that are goingto be combined may be in the form of:

red at intensity one at 2302,

red at intensity two at 2304,

blue at intensity one at 2302,

blue at intensity two at 2304,

green at intensity one at 2302,

green at intensity two at 2304.

Alternatively, the system may be cycled in the form of:

-   -   red at intensity one at 2302,    -   blue at intensity one at 2302,    -   green at intensity one at 2302,    -   red at intensity two at 2304,    -   blue at intensity two at 2304,    -   green at intensity two at 2304.

In such an embodiment a first image may be derived from the intensityone values, and a second image may be derived from the intensity twovalues, and then combined or processed as complete image data sets at2310 rather than their component parts.

It is contemplated to be within the scope of this disclosure that anynumber of emission partitions may be used in any order. As seen in FIG.23, “n” is used as a variable to denote any number of electromagneticpartitions and “m” is used to denote any level of intensity for the “n”partitions. Such a system may be cycled in the form of:

-   -   n at intensity m at 2306,    -   n+1 at intensity m+1,    -   n+2 at intensity m+2,    -   n+i at intensity m+j at 2308.

Accordingly, any pattern of serialized cycles can be used to produce thedesired image correction wherein “i” and “j” are additional valueswithin the operation range of the imaging system.

Digital color cameras incorporate an image processing stage for thepurpose of maximizing the fidelity of color reproduction. This isaccomplished by means of a 3×3 matrix known as the Color CorrectionMatrix (CCM):

$\begin{bmatrix}R \\G \\B\end{bmatrix}_{OUT} = {\begin{bmatrix}R \\G \\B\end{bmatrix}_{IN}\begin{bmatrix}a & b & c \\d & e & f \\g & h & i\end{bmatrix}}$

The terms in the CCM are tuned using a set of reference colors (e.g.,from a Macbeth chart) to provide the best overall match to the sRGBstandard color space. The diagonal terms, a, e and i, are effectivelywhite balance gains. Typically though, the white balance is appliedseparately and the sums of horizontal rows are constrained to be unity,in order no net gain is applied by the CCM itself. The off-diagonalterms effectively deal with color crosstalk in the input channels.Therefore Bayer sensors have higher off-diagonals than 3-chip camerassince the color filer arrays have a lot of response overlap betweenchannels.

There is a signal-to-noise ratio penalty for color correction which isdependent on the magnitude of the off-diagonal terms. A hypotheticalsensor with channels that perfectly matched the sRGB components wouldhave the identity matrix CCM:

$\begin{bmatrix}R \\G \\B\end{bmatrix}_{OUT} = {\begin{bmatrix}R \\G \\B\end{bmatrix}_{IN}\begin{bmatrix}1 & 0 & 0 \\0 & 1 & 0 \\0 & 0 & 1\end{bmatrix}}$

The signal to noise ratio evaluated in the green channel, for a perfectwhite photosignal of 10,000 e-per pixel (neglecting read noise) for thiscase would be:

${SNR} = {\frac{10,000}{\sqrt{10,000}} = 100}$

Any departure from this degrades the SNR. Take e.g. the following CCMwhich has values that would not be unusual for a Bayer CMOS sensor:

$\begin{bmatrix}R \\G \\B\end{bmatrix}_{OUT} = {\begin{bmatrix}R \\G \\B\end{bmatrix}_{IN}\begin{bmatrix}2.6 & {- 1.4} & {- 0.2} \\{- 0.3} & 1.6 & {- 0.3} \\0 & {- 0.6} & 1.6\end{bmatrix}}$

In this case the green SNR:

${SNR} = {\frac{\left( {{- 3000} + {16,000} - 3000} \right)}{\sqrt{\left( {3000 + {16,000} + 3000} \right)}} = 67.1}$

FIG. 24 shows the result of a full SNR simulation using D65 illuminationfor a typical Bayer sensor CCM for the case of using the identity matrixversus the tuned CCM. The SNR evaluated for the luminance component isabout 6 dB worse as a consequence of the color correction.

The system described in this disclosure uses monochromatic illuminationat three discrete wavelengths, therefore there is no color crosstalk perse. The crosses in FIG. 25 indicate the positions of three wavelengthswhich are available via laser diode sources (465, 532 & 639 nm),compared the sRGB gamut which is indicated by the triangle.

The off-diagonal terms for the CCM is in this case are drasticallyreduced, compared with Bayer sensors, which provides a significant SNRadvantage.

FIG. 26 illustrates an imaging system having increased dynamic range asprovided by the pixel configuration of the pixel array of the imagesensor. As can be seen in the figure, adjacent pixels 2602 and 2604 maybe set at differing sensitivities such that each cycle includes dataproduced by pixels that are more and less sensitive with respect to eachother. Because a plurality of sensitivities can be recorded in a singlecycle of the array the dynamic range may be increased if recorded inparallel, as opposed to the time dependent serial nature of otherembodiments.

In an embodiment, an array may comprise rows of pixels that may beplaced in rows based on their sensitivities. In an embodiment, pixels ofdiffering sensitivities may alternate within a row or column withrespect to its nearest neighboring pixels so as to from a checkerboardpattern throughout the array based on those sensitivities. The above maybe accomplished through any pixel circuitry share arrangement or in anystand-alone pixel circuit arrangement.

Wide dynamic range can be achieved by having multiple global TX, each TXfiring only on a different set of pixels. For example in global mode, aglobal TX1 signal is firing a set 1 of pixels, a global TX2 signal isfiring a set 2 of pixels . . . a global TXn signal is firing a set n ofpixels.

Based on FIG. 11, FIG. 27A shows a timing example for 2 different pixelsensitivities (dual pixel sensitivity) in the pixel array. In this case,global TX1 signal fires half of the pixels of the array and global TX2fires the other half of the pixels. Because global TX1 and global TX2have different “on” to “off” edge positions, integrated light isdifferent between the TX1 pixels and the TX2 pixels. FIG. 27B shows adifferent embodiment of the timing for dual pixel sensitivity. In thiscase, the light pulse is modulated twice (pulse duration and/oramplitude). TX1 pixels integrate P1 pulse and TX2 pixels integrate P1+P2pulses. Separating global TX signals can be done many ways. Thefollowing are examples:

Differentiating TX lines from each row; and

Sending multiple TX lines per row, each addressing a different set ofpixels.

In one implementation, a means of providing wide-dynamic range video isdescribed, which exploits the color pulsing system described in thisdisclosure. The basis of this is to have multiple flavors of pixels, orpixels that may be tuned differently, within the same monochrome arraythat are able to integrate the incident light for different durationswithin the same image frame. An example of the pixel arrangement in thearray of such a sensor would be a uniform checkerboard patternthroughout, with two independently variable integration times. For sucha case, it is possible to provide both red and blue information withinthe same image frame. In fact, it is possible to do this at the sametime as extending the dynamic range for the green frame, where it ismost needed, since the two integration times can be adjusted on a frameby frame basis. The benefit is that the color motion artifacts are lessof an issue if all the data is derived from two frames versus three.There is of course a subsequent loss of spatial resolution for the redand blue data, but that is of less consequence to the image qualitycompared with green, since the luminance component is dominated by greendata.

An inherent property of the monochrome wide-dynamic range (WDR) array isthat the pixels that have the long integration time must integrate asuperset of the light seen by the short integration time pixels. Forregular wide-dynamic range operation in the green frames, that isdesirable. For the red and blue frames it means that the pulsing must becontrolled in conjunction with the exposure periods so as to, e.g.,provide blue light from the start of the long exposure and switch to redat the point that the short exposure pixels are turned on (both pixeltypes have their charges transferred at the same time).

At the color fusion stage, the two flavors of pixels are separated intotwo buffers. The empty pixels are then filled in using, e.g., linearinterpolation. At this point, one buffer contains a full image of bluedata and the other red+blue. The blue buffer may be subtracted from thesecond buffer to give pure red data.

FIGS. 28A-28C illustrate the use of a white light emission that ispulsed and/or synced, or held constant, with a corresponding colorsensor. As can be seen in FIG. 28A, a white light emitter may beconfigured to emit a beam of light during the blanking time of acorresponding sensor so as to provide a controlled light source in acontrolled light environment. The light source may emit a beam at aconstant magnitude and vary the duration of the pulse as seen in FIG.28A, or may hold the pulse constant with varying the magnitude in orderto achieve correctly exposed data as illustrated in FIG. 28B.Illustrated in FIG. 28C is a graphical representation of a constantlight source that can be modulated with varying current that iscontrolled by and synced with a sensor.

In an embodiment, white light or multi-spectrum light may be emitted asa pulse, if desired, in order to provide data for use within the system(illustrated best in FIGS. 28A-28C). White light emissions incombination with partitions of the electromagnetic spectrum may beuseful for emphasizing and de-emphasizing certain aspects within ascene. Such an embodiment might use a pulsing pattern of:

-   -   Green pulse;    -   Red pulse;    -   Blue pulse;    -   Green pulse;    -   Red pulse;    -   Blue pulse;    -   White light (multi-spectrum) pulse;    -   (Repeat)

Any system using an image sensor cycle that is at least two times fasterthan the white light cycle is intended to fall within the scope of thedisclosure. It will be appreciated that any combination of partitions ofthe electromagnetic spectrum is contemplated herein, whether it be fromthe visible or non-visible spectrum of the full electromagneticspectrum.

FIGS. 29A and 29B illustrate a perspective view and a side view,respectively, of an implementation of a monolithic sensor 2900 having aplurality of pixel arrays for producing a three dimensional image inaccordance with the teachings and principles of the disclosure. Such animplementation may be desirable for three dimensional image capture,wherein the two pixel arrays 2902 and 2904 may be offset during use. Inanother implementation, a first pixel array 2902 and a second pixelarray 2904 may be dedicated to receiving a predetermined range of wavelengths of electromagnetic radiation, wherein the first pixel array isdedicated to a different range of wave length electromagnetic radiationthan the second pixel array.

FIGS. 30A and 30B illustrate a perspective view and a side view,respectively, of an implementation of an imaging sensor 3000 built on aplurality of substrates. As illustrated, a plurality of pixel columns3004 forming the pixel array are located on the first substrate 3002 anda plurality of circuit columns 3008 are located on a second substrate3006. Also illustrated in the figure are the electrical connection andcommunication between one column of pixels to its associated orcorresponding column of circuitry. In one implementation, an imagesensor, which might otherwise be manufactured with its pixel array andsupporting circuitry on a single, monolithic substrate/chip, may havethe pixel array separated from all or a majority of the supportingcircuitry. The disclosure may use at least two substrates/chips, whichwill be stacked together using three-dimensional stacking technology.The first 3002 of the two substrates/chips may be processed using animage CMOS process. The first substrate/chip 3002 may be comprisedeither of a pixel array exclusively or a pixel array surrounded bylimited circuitry. The second or subsequent substrate/chip 3006 may beprocessed using any process, and does not have to be from an image CMOSprocess. The second substrate/chip 3006 may be, but is not limited to, ahighly dense digital process in order to integrate a variety and numberof functions in a very limited space or area on the substrate/chip, or amixed-mode or analog process in order to integrate for example preciseanalog functions, or a RF process in order to implement wirelesscapability, or MEMS (Micro-Electro-Mechanical Systems) in order tointegrate MEMS devices. The image CMOS substrate/chip 3002 may bestacked with the second or subsequent substrate/chip 3006 using anythree-dimensional technique. The second substrate/chip 3006 may supportmost, or a majority, of the circuitry that would have otherwise beenimplemented in the first image CMOS chip 3002 (if implemented on amonolithic substrate/chip) as peripheral circuits and therefore haveincreased the overall system area while keeping the pixel array sizeconstant and optimized to the fullest extent possible. The electricalconnection between the two substrates/chips may be done throughinterconnects 3003 and 3005, which may be wirebonds, bump and/or TSV(Through Silicon Via).

FIGS. 31A and 31B illustrate a perspective view and a side view,respectively, of an implementation of an imaging sensor 3100 having aplurality of pixel arrays for producing a three dimensional image. Thethree dimensional image sensor may be built on a plurality of substratesand may comprise the plurality of pixel arrays and other associatedcircuitry, wherein a plurality of pixel columns 3104 a forming the firstpixel array and a plurality of pixel columns 3104 b forming a secondpixel array are located on respective substrates 3102 a and 3102 b,respectively, and a plurality of circuit columns 3108 a and 3108 b arelocated on a separate substrate 3106. Also illustrated are theelectrical connections and communications between columns of pixels toassociated or corresponding column of circuitry.

It will be appreciated that the teachings and principles of thedisclosure may be used in a reusable device platform, a limited usedevice platform, a re-posable use device platform, or asingle-use/disposable device platform without departing from the scopeof the disclosure. It will be appreciated that in a re-usable deviceplatform an end-user is responsible for cleaning and sterilization ofthe device. In a limited use device platform the device can be used forsome specified amount of times before becoming inoperable. Typical newdevice is delivered sterile with additional uses requiring the end-userto clean and sterilize before additional uses. In a re-posable usedevice platform a third-party may reprocess the device (e.g., cleans,packages and sterilizes) a single-use device for additional uses at alower cost than a new unit. In a single-use/disposable device platform adevice is provided sterile to the operating room and used only oncebefore being disposed of.

An embodiment of an emitter may employ the use of a mechanical shutterand filters to create pulsed color light. As illustrated in FIG. 32, analternate method to produce pulsed color light, using a white lightsource and a mechanical color filter and shutter system 3200. The wheelcould contain a pattern of translucent color filter windows and opaquesections for shuttering. The opaque sections would not allow lightthrough and would create a period of darkness in which the sensorread-out could occur. The white light source could be based on anytechnology: laser, LED, xenon, halogen, metal halide, or other. Thewhite light can be projected through a series of color filters 3207,3209 and 3211 of the desired pattern of colored light pulses. Oneembodiment pattern could be Red filter 3207, Green filter 3209, Bluefilter 3211, Green filter 3209. The filters and shutter system 3200could be arranged on a wheel that spins at the required frequency to bein sync with the sensor such that knowledge of the arch length and rateof rotation of the mechanical color filters 3207, 3209 and 3211 andshutters 3205 system would provide timing information for the operationof a corresponding monochromatic image sensor.

Illustrated in FIG. 33 an embodiment may comprise a pattern of onlytranslucent color filters 3307, 3309 and 3311 on a filter wheel 3300. Inthe present configuration, a different shutter may be used. The shuttercould be mechanical and could dynamically adjust the “pulse” duration byvarying is size. Alternately the shutter could be electronic andincorporated into the sensor design. A motor spinning the filter wheel3300 will need to communicate with, or be controlled in conjunction withthe sensor such that knowledge of the arch length and rate of rotationof the mechanical color filters 3307, 3309 and 3311 system would providetiming information for the operation of the corresponding monochromaticimage sensor. The control system will need to know the proper colorfilter for each frame captured by the sensor so that the full-colorimage frame can be reconstructed properly in the ISP. A color pattern ofRGBG is shown, but other colors and/or patterns could be used ifadvantageous. The relative size of the color sections is shown as equal,but could be adjusted if advantageous. The mechanical structure of thefilter is shown as a circle moving rotationally, but could berectangular with a linear movement, or a different shape with adifferent movement pattern.

As illustrated FIG. 34, an embodiment for pulsing color light mayconsist of a mechanical wheel or barrel that holds the electronics andheat sinks for Red, Green, Blue or White LEDS. The LEDs would be spacedat the distance that would be related to the rate of spin or twist ofthe barrel or wheel to allow for timing of light pulsing consistent withother embodiments in the patent. The wheel or barrel would be spun usingan electrical motor and a mechanical bracket attaching the wheel orbarrel to the electrical motor. The motor would be controlled using amicrocontroller, FPGA, DSP, or other programmable device that wouldcontain a control algorithm for proper timing as described in thepatent. There would be a mechanical opening on one side that would beoptically coupled to a fiber optic to transport the fiber to the end ofthe scopes with the methods described in the patent. This coupling couldalso have a mechanical aperture that could open and close to control theamount of light allowed down the fiber optic cable. This would be amechanical shutter device alternatively one could use the electronicshutter that is designed into a CMOS or CCD type sensor. This devicewould be difficult to control and calibrate in production but is anotherway one could get pulsed light into our system.

Illustrated in FIG. 35, is an embodiment of an emitter comprising alinear filter and shutter mechanism to provide pulsed electromagneticradiation.

Illustrating in FIG. 36, is an embodiment of an emitter comprising aprism filter and shutter mechanism to provide pulsed electromagneticradiation.

Additionally, the teachings and principles of the disclosure may includeany and all wavelengths of electromagnetic energy, including the visibleand non-visible spectrums, such as infrared (IR), ultraviolet (UV), andX-ray.

It will be appreciated that various features disclosed herein providesignificant advantages and advancements in the art. The following claimsare exemplary of some of those features.

In the foregoing Detailed Description of the Disclosure, variousfeatures of the disclosure are grouped together in a single embodimentfor the purpose of streamlining the disclosure. This method ofdisclosure is not to be interpreted as reflecting an intention that theclaimed disclosure requires more features than are expressly recited ineach claim. Rather, inventive aspects lie in less than all features of asingle foregoing disclosed embodiment.

It is to be understood that the above-described arrangements are onlyillustrative of the application of the principles of the disclosure.Numerous modifications and alternative arrangements may be devised bythose skilled in the art without departing from the spirit and scope ofthe disclosure and the appended claims are intended to cover suchmodifications and arrangements.

Thus, while the disclosure has been shown in the drawings and describedabove with particularity and detail, it will be apparent to those ofordinary skill in the art that numerous modifications, including, butnot limited to, variations in size, materials, shape, form, function andmanner of operation, assembly and use may be made without departing fromthe principles and concepts set forth herein.

Further, where appropriate, functions described herein can be performedin one or more of: hardware, software, firmware, digital components, oranalog components. For example, one or more application specificintegrated circuits (ASICs) or field programmable gate arrays (FPGAs)can be programmed to carry out one or more of the systems and proceduresdescribed herein. Certain terms are used throughout the followingdescription and claims to refer to particular system components. As oneskilled in the art will appreciate, components may be referred to bydifferent names. This document does not intend to distinguish betweencomponents that differ in name, but not function.

The foregoing description has been presented for the purposes ofillustration and description. It is not intended to be exhaustive or tolimit the disclosure to the precise form disclosed. Many modificationsand variations are possible in light of the above teaching. Further, itshould be noted that any or all of the aforementioned alternateimplementations may be used in any combination desired to formadditional hybrid implementations of the disclosure.

Further, although specific implementations of the disclosure have beendescribed and illustrated, the disclosure is not to be limited to thespecific forms or arrangements of parts so described and illustrated.The scope of the disclosure is to be defined by the claims appendedhereto, any future claims submitted here and in different applications,and their equivalents.

What is claimed is:
 1. A digital imaging method for use in ambient light deficient environments with an endoscope comprising an image sensor having optical black back rows and optical black front rows, the digital imaging method comprising: pulsing, by an emitter, a first pulse of electromagnetic radiation at a wavelength to cause illumination within an ambient light deficient environment; wherein said first pulse is within a first wavelength range that comprises a first portion of an electromagnetic spectrum and wherein said pulsing occurs during a blanking period, wherein the blanking period begins when optical black back rows of the image sensor start being read during a first sensor operation cycle and ends when optical black front rows of the image sensor are done being read during a sensor operation cycle immediately following the first sensor operation cycle; sensing electromagnetic radiation from the first pulse with a pixel array of the image sensor; wherein the electromagnetic radiation sensed by said pixel array from the first pulse is read out of the pixel array during a frame readout period of the sensor operation cycle immediately following the first sensor operation cycle; wherein a duration of the frame readout period comprises an amount of time required to read each pixel in the pixel array of the image sensor, wherein the electromagnetic radiation emitted as the first pulse and sensed by said pixel array is read out of the pixel array as a first data set.
 2. The method of claim 1, wherein the pulsing further comprises emitting a plurality of pulses of electromagnetic radiation in sequence to cause illumination, wherein the first pulse is within the first wavelength range that is only a portion of the electromagnetic spectrum, wherein a second pulse is within a second wavelength range that is only a portion of the electromagnetic spectrum, wherein a third pulse is within a third wavelength range that is only a portion of the electromagnetic spectrum, wherein the pulses are pulsed at a predetermined interval, wherein sensing electromagnetic radiation further comprises sensing electromagnetic radiation from the plurality of pulses of electromagnetic radiation in sequence; wherein the electromagnetic radiation sensed during the first pulse is read out of the pixel array as the first data set; wherein the electromagnetic radiation sensed during the second pulse is read out of the pixel array as a second data set; and wherein the electromagnetic radiation sensed during the third pulse is read out of the pixel array as a third data set.
 3. The method of claim 2, wherein the first pulse is of a green visible light spectrum range, and wherein the second pulse is of a red visible light spectrum, and wherein the third pulse is of a blue visible light spectrum.
 4. The method of claim 2, wherein one of the pulses is from a non-visible range of electromagnetic spectrum.
 5. The method of claim 2, wherein the image sensor is configured to sense any of the first pulse, the second pulse, and the third pulse equally.
 6. The method of claim 2, wherein the image sensor is configured to sense electromagnetic radiation in the visible portion of the electromagnetic spectrum, the infrared portion of the electromagnetic spectrum, the ultraviolet portion of the electromagnetic spectrum, and the X-ray portion of the electromagnetic spectrum.
 7. The method of claim 1, wherein the pixel array comprises a plurality of subsets of pixels, wherein the plurality of subsets of pixels each have different sensitivities.
 8. The method of claim 7, wherein variations in image sensor sensitivity are adjusted by a global reset mechanism.
 9. The method of claim 7, further comprising utilizing the plurality of pixel sensitivities for the purpose of extending the dynamic range of the system.
 10. The method of claim 1, further comprising: pulsing, by the emitter, a second pulse that is within a second wavelength range that is only a portion of the electromagnetic spectrum; sensing electromagnetic radiation from the second pulse with the pixel array of the image sensor; reading out the electromagnetic radiation emitted as the second pulse and sensed by said pixel array as a second data set; generating a combined image, the combined image comprising the first data set and the second data set; and generating a video stream comprising a plurality of images wherein one or more of the plurality of images is the combined image.
 11. The method of claim 1, further comprising: pulsing, by the emitter, a plurality of pulses of electromagnetic radiation, each of which is a portion of the electromagnetic spectrum; sensing electromagnetic radiation from the plurality of pulses of electromagnetic radiation with the pixel array of the image sensor; reading out the electromagnetic radiation sensed by the pixel array from the plurality of pulses of electromagnetic radiation as a plurality of data sets; generating a plurality of images, each image of the plurality of images comprising one or more of the plurality of data sets; and combining the plurality of images in sequence to generate the video stream.
 12. The method of claim 2, further comprising: generating a combined image comprising the first data set, the second data set, and the third data set; and generating the video stream comprising a plurality of images wherein one or more of the plurality of images is the combined image. 